Conventional fuel injection systems for two-stroke and four-stroke internal combustion engines include either a poppet injector responsive to fuel pressure for opening the injector or an electromagnetic injector responsive to application of electrical energy to open the injector. In both cases, the injector construction is expensive and subject to failure during operation. It is therefore a general object of the present invention to provide a fuel injection system for an internal combustion engine that features an improved injector construction.
A fuel injection system in accordance with a presently preferred embodiment of the invention includes an injector having a housing with inlet and outlet ports, and a pintle movable within the housing for selectively opening and closing communication between the inlet and outlet port. The inlet port is connected to a source of fuel under pressure, while the outlet port is connected to a nozzle for delivering fuel under pressure to the engine. First magnetic material is coupled to the pintle, and second magnetic material is mounted for motion adjacent to the first magnetic material in synchronism with operation of the engine, such that magnetic forces imparted on the first magnetic material as the second magnetic material moves therepast moves the pintle to open communication between the inlet and outlet ports, and thereby delivers fuel under pressure from the source to the nozzle. Magnets that attract each other or oppose each other may be employed depending upon desired nozzle configuration. Opposing magnets are disclosed for purposes of explanation herein. In the preferred embodiment of the invention, a cam mechanism is rotatably positioned within the pintle housing and operatively coupled to the pintle for adjustably varying stroke of the pintle within the housing, and thereby varying time duration during which the injector opens communication between the fuel source and the nozzle.
In various embodiments of the invention, the injector nozzle is disposed in the transfer port of a two-stroke engine, in the combustion cylinder of the engine for direct fuel injection, or in the air intake manifold of a ported engine for indirect fuel injection. An air pump may deliver pulsations of air under pressure to the injector nozzle to assist atomization of the fuel. In the preferred embodiments of the invention, the second magnet is mounted on the engine flywheel, and the pintle housing, or both the pintle housing and the air pump, are mounted on the engine crankcase externally adjacent to the flywheel and responsive to passage of the flywheel-mounted magnet for delivering air and/or fuel pulses to the injector nozzle.